Catalyst carrier body with passivation layer and method for producing the same

ABSTRACT

A catalyst carrier body includes at least one housing, a honeycomb body and a passivation layer which includes a multiplicity of separate crystal agglomerations with an averaged height lying in the range of 0.3 to 1.5 μm. Various production methods are proposed which are suitable, in particular, for producing such catalyst carrier bodies. Thus, the formation of the passivation layer takes place by the blending and/or mixing of an adhesive with a passivating substance and subsequently applying the adhesive, or by roughening a region using a blast-cutting manufacturing method with corundum particles being employed as the blasting medium. A barrier is thereby provided in a very simple and cost-effective way which, for example during the formation of brazed connections, prevents the then liquid brazing material from being distributed beyond the desired tying regions as a result of capillary effects.

CROSS-REFERENCE TO RELATED APPLICATIONS:

This is a continuing application, under 35 U.S.C. § 120, of copendingInternational Application No. PCT/EP03/11503, filed Oct. 17, 2003, whichdesignated the United States; this application also claims the priority,under 35 U.S.C § 119, of German Patent Application 102 51 624.3, filedOct. 18, 2002; the prior applications are herewith incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a catalyst carrier body which includesat least one housing with an inside, as well as a honeycomb body. Theinvention also relates to a method for producing a catalyst carrierbody. Such catalyst carrier bodies are used, in particular, for thecleaning of exhaust gases of mobile internal combustion engines such as,for example, gasoline or diesel engines in motor vehicle engineering.

Catalyst carrier bodies in motor vehicle construction are conventionallyprovided with a carrier layer (in particular a wash coat) which isdistinguished by a very large surface and is conventionally impregnatedwith at least one catalytically active material (for example, platinum,rhodium or the like). When contact occurs between the exhaust gas andthose catalytically active materials, a reduction in the pollutants,such as, for example, carbon monoxide, unsaturated hydrocarbons,nitrogen monoxide, etc., which are contained in the exhaust gas, takesplace. In order, from the outset, to provide a relatively large surfaceof the carrier layer, the catalyst carrier bodies are conventionallyconstructed as honeycomb bodies which have a multiplicity of passagesthrough which a fluid (in particular, exhaust gas) is capable offlowing. Ceramic, extruded and metallic honeycomb bodies are known inthat context. The honeycomb bodies are generally introduced into ahousing which, in turn, is integrated directly into the exhaust pipe of,for example, a passenger car. In a mobile exhaust system of that type,the catalyst carrier body is exposed to high thermal and dynamic loads.

The thermal loads result, for example, on one hand, from the temperatureof the exhaust gas itself, which temperature increases when the catalystcarrier body is disposed nearer to the internal combustion engine. Onthe other hand, chemical catalytic conversion also leads to a rise intemperature of the catalyst carrier body, since that conversiongenerally proceeds exothermally, so that, under certain circumstances,temperatures are reached which are markedly higher than the exhaust gastemperature itself (up to 1300° C.). The important factors with regardto dynamic loads arise as a result of the combustion process and ofexternal vibration excitations. Since the combustion process in theinternal combustion engine takes place intermittently, the pressurepulses resulting therefrom are propagated periodically through theexhaust system. External vibration excitation occurs, for example, dueto unevennesses of a road over which the motor vehicle is moving.

Due to such high thermal and dynamic loads, a permanent connection ofthe honeycomb body to the housing is particularly expedient. On onehand, the connection must be suitable for compensating for a differentthermal expansion behavior of the honeycomb body relative to the housing(precisely with regard to the time after a new start or a restart of theinternal combustion engine) and, on the other hand, a detachment of thehoneycomb body from the housing must be avoided in the long term.

In this respect, reference may be made first to a method for producing ahoneycomb body which may be gathered from International Publication No.WO 99/37896, corresponding to U.S. Pat. Nos. 6,425,517, 6,497,039 and6,634,542. Those disclosures state that the honeycomb body and thecasing tube have a differing thermal expansion behavior due to theirdifferent material properties and because of different temperaturesduring operation. The aim, therefore, is to avoid a rigid connectionbetween the honeycomb body and the casing tube at least at one endregion of the honeycomb body or, in any event, in defined partialregions. For that reason, the encased honeycomb body described inInternational Publication No. WO 99/37896, corresponding to U.S. Pat.Nos. 6,425,517, 6,497,039 and 6,634,542, is constructed with a sleevewhich, in spite of manufacturing tolerances of the casing tube and ofthe honeycomb body, is intended to ensure that direct brazed connectionsbetween the honeycomb body and the casing tube in the at least one endregion of the honeycomb body are avoided. Further embodiments of suchsleeves may also be gathered, for example, from InternationalPublication No. WO 01/79670, corresponding to U.S. Patent ApplicationPublication No. US 2003/0007906 and International Publication No. WO01/53668, corresponding to U.S. Patent Application Publication No. US.2003/0021740. The contents of the disclosures of the above-mentioneddocuments is fully incorporated herein.

Precisely with regard to the use of metallic honeycomb bodies and of apermanent tying or connection into a metallic housing, it is furtherknown to make the connection of the honeycomb body to the housingthrough an intermediate layer which is connected on its inside to thehoneycomb body and at its outside to the housing. Such an intermediatelayer may be gathered, for example, from Japanese Patent Publication JP04-222636 A. The intermediate layer is constructed therein as acorrugated metal sheet and is connected, on one hand, to the honeycombbody and, on the other hand, to the housing. In that case, it is statedthat the corrugated metal sheet can experience deformation in the eventof a radial expansion of the honeycomb body. In order to ensure such adeformation, it is proposed therein that a connection of the corrugatedmetal sheet to the honeycomb body not be disposed in the same crosssection as a connection to the housing. Under those circumstances, anexpansion and contraction of the honeycomb body in the axial directionwould also be ensured.

Further, what may be referred to as contraction limiters are known fromGerman Published, Non-Prosecuted Patent Application DE 101 37 897 A1,corresponding to U.S. Patent Application Publication No. US 2004/0152595A1. Reference to the contents of the disclosure thereof is made fullyherein. The at least one contraction limiter, which is disposed betweenthe honeycomb body and the housing, causes an outwardly directed tensionon at least part of the honeycomb body, so that the mean initialdiameter of the matrix during and/or after thermal stress decreases byat most 5%, preferably even only by at most 2%. In that respect, it isexplained that, because of the different cooling behavior in edgeregions and in core regions, known metallic honeycomb bodies no longerassume their original, in particular cylindrical configuration afterrepeated thermal alternating stress but, instead, reduce their volumeand have a, for example, barrel-like contour. The result thereof, inparticular, is that, between the matrix and the housing, a relativelylarge annular gap is formed, through which, particularly duringoperation of the honeycomb body in the exhaust system of an internalcombustion engine, the uncleaned exhaust gas flows, and, consequently,effective cleaning according to the statutory regulations cannot beensured. The above-mentioned contraction limiters serve for compensatingfor or preventing such a barrel-like contour of the honeycomb body.

In all of those configurations of a catalyst carrier body, it isparticularly important to define exactly the connection regions requiredfor that purpose between the honeycomb body and the housing or betweenthe honeycomb body and the sleeve or between the sleeve and the housing.In particular, in production, care must be taken to ensure that, forexample during the brazing of the components disposed adjacently oneanother, a flow of brazing material into portions outside the desiredconnection regions is prevented. For that purpose, for example, measuresare known which prevent a connection of metal surfaces duringhigh-temperature processing (such as, for example, sintering orbrazing). Those measures mostly contain fine ceramic particles which areapplied to the corresponding surface through the use of a binder. Thebinder is volatile at even relatively low temperatures. That substanceis also known, inter alia, as brazing material stop.

Reference may be made at this juncture, in particular, to InternationalPublication No. WO 01/79669, corresponding to U.S. Pat. No. 6,673,466and U.S. Patent Application Publication No. US 2003/0049484, thecontents of the disclosures of which are likewise fully incorporatedinto the description herein. Those disclosures describe a productionmethod for a catalyst carrier body. The housing is constructed, in atleast one portion of an inner wall, with a passivation layer for thecontrolled prevention of a brazed connection to the honeycomb body. Thepassivation layer in that case takes the form of a surface oxide layer,in particular of a ceramic application layer. In order to produce such apassivation layer, it is proposed to heat the housing selectively, in aspatially limited manner, heat it inductively and treat it chemicallyand to apply the ceramic layer to the housing through the use of flamespraying. The alternatives, disclosed therein, for producing such apassivation layer, have proven very appropriate in the past, but in thatcase it is a predominant requirement that the housing be subjected toadditional thermal treatment. That is unfavorable, for example in termsof production costs, since there has to be passage through amultiplicity of different processing stations, and under certaincircumstances, in turn, standstill times are necessary during which thecomponent is heated or cooled.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a catalystcarrier body with a passivation layer and a method for producing thesame, which overcome the hereinafore-mentioned disadvantages of theheretofore-known devices and methods of this general type, in which thecatalyst carrier body can be produced by a simple and cost-effectiveprocedure that is careful in terms of the material used, which ensuresexactly delimited connection regions of components of the catalystcarrier body that are to be connected to one another and in whichproduction methods make it possible, without a high outlay in technicalterms, to provide passivation layers in desired regions, while alsousing as small an amount of passivating materials as possible.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a catalyst carrier body, comprising atleast one housing having an inside, a honeycomb body connected to theinside of the at least one housing by technical joining in a tyingregion, and at least one passivation layer delimiting the tying region.The passivation layer includes a multiplicity of separate crystalagglomerations with an averaged height lying in a range of 0.3 to 1.5μm.

It is accordingly proposed herein that the region in which a tyingtogether of the housing and the honeycomb body is to be prevented not becovered completely by a unitary sheet-like passivation layer, butinstead an open-pored rough fissured passivation layer is formed. Thishas several advantages, for example, only a small amount of material ofthe passivation medium (such as, for example, Al₂O₃) needs to be used.Furthermore, concentration differences which are generated on thesurface in a controlled manner are, for example, conducive to adiffusion and oxidation of aluminum contained in the metal of thehousing and/or of the honeycomb body. In this case, it is particularlyadvantageous if a multiplicity of crystal agglomerations are delimitedand spaced apart from one another, in particular to such an extent thatthe distance from the adjacent crystal agglomeration is greater than itsheight.

In accordance with another feature of the invention, the crystalagglomerations are disposed on the inside of the housing or on at leastone sleeve which is positioned between the housing and the honeycombbody. The inside of the housing or the sleeve is preferably roughened inthe region of the passivation layer. A thus fissured surface of thepassivation region can thereby also be achieved in terms of seriesmanufacture with a high degree of process reliability.

With the objects of the invention in view, there is also provided amethod for producing a catalyst carrier body, which comprises providingat least one housing having an inside, and providing a honeycomb body. Aregion of the inside of the housing and/or the honeycomb body isroughened using a blast-cutting manufacturing method with corundumparticles employed as a blasting medium. The honeycomb body is insertedinto the housing and technical joining connections are formed. With theobjects of the invention in view, there is additionally provided amethod for producing a catalyst carrier body, which comprises providingat least one housing with an inside, providing at least one sleeve, andproviding a honeycomb body. A region of the sleeve is roughened using ablast-cutting manufacturing method with corundum particles employed as ablasting medium. The at least one sleeve is introduced into the housingor the at least one sleeve is placed around the honeycomb body. Thehoneycomb body is inserted into the housing and technical joiningconnections are formed.

The manufacturing method of blast-cutting has proved particularlyappropriate in tests due to its flexible possibilities of use. Inblast-cutting, cutting grains are thrown loosely onto a processinglocation. Since the action of the cutter is governed mainly by thekinetic energy of the grain, the active principle of cutter engagementis energy-bound. It is preferable in this case to use corundumparticles, in particular with a size of 10 μm to 20 μm, which areblasted through the use of an energy carrier, by the pressure orcentrifugal method, onto the surface to be treated. The use of corundumparticles has the advantage that at least fractions of the particlesthemselves settle on the surface of the blasting component or areconducive, on the surface, to a diffusion and oxidation of aluminumcontained in the metal. Therefore, as a rule, no further operation isrequired in order to apply another or further material having apassivating action in this region. As a rule, through the use of anappropriate blast nozzle, all of those regions of the housing, of thehoneycomb body and/or of the sleeve which are relevant in this case caneasily be reached even fully automatically. This method is consequentlyhighly suitable for series production which, for example in motorvehicle construction, is customary in the production of catalyst carrierbodies.

With the objects of the invention in view, there is furthermore provideda method for producing a catalyst carrier body, which comprisesproviding at least one housing with an inside, and providing a honeycombbody. An adhesive is blended and/or mixed with a passivating substance.The adhesive having the passivating substance is applied to the insideof the housing. The honeycomb body is inserted into the housing andtechnical joining connections are formed.

An important aspect, in this case, is the use of an adhesive which atthe same time has a passivating substance. Adhesive of this type isapplied to the inside of the housing in order to fix the honeycomb bodywithin the housing, so that it is subsequently possible to introduceinto the honeycomb structure or between the housing and the honeycombstructure the substances which serve for forming the desired technicaljoining connections. Thus, in particular, the adhesive differs from theknown binders in that the adhesive primarily has the function of fixingthe honeycomb structure at least temporarily in the housing, that is tosay not only providing a bonding action between the passivating layerand the surface. The preferred manner of producing the technical joiningconnection is by brazing. However, a sintering process or even weldingmay be used as well.

The need for prior fixing arises, in particular, with regard tohoneycomb bodies which have a plurality of at least partially structuredmetal foils. Conventionally, these metal foils are coiled, wound and/orstacked spirally, in an S-shaped or U-shaped manner or in a similar way.This “loose” stack of metal foils is subsequently introduced into thehousing through the use of a corresponding device, in which case it isparticularly important that the relative configuration of the metalfoils which has been produced is substantially preserved. Thispreservation of the relative configuration of the metal foils isimportant precisely also with regard to subsequent manufacturingprocesses, since in this case, for example, the supply of adhesiveand/or brazing material is carried out “by contact”. That is to say, theabove-mentioned substances, as a rule, are not sprayed on, but areapplied or introduced at least partially by contact of an applicatordevice with the metal foils. Since, in this respect, it is not possibleto ensure that uniform contacting of all of the metal foils takes placesimultaneously, the composite structure or stack of metal foils isprotected against a mutual displacement of the metal foils through theuse of the adhesive proposed herein.

In addition to the function of fixing the honeycomb body in early phasesof the production process, the adhesive makes it possible, moreover, togenerate a passivation layer. For this purpose, it is necessary that theadhesive action of the adhesive recedes into the background, preferablyeven disappears completely, in a later phase of the production process.It is necessary, however, at least to ensure that, in the finishedcatalyst carrier body, the adhesive action of the adhesive issignificantly lower than the connecting forces of the technical joiningconnections, so that the resulting adhesive connections do not cause anytensions between the honeycomb body and the housing in the event of arelative movement of these components.

After the adhesive has substantially lost its adhesive action, apassivation layer is formed at the corresponding location on the insideof the housing. The passivation layer, for example, preventssubsequently applied and heated brazing material from settling in thisregion. In this respect, it is particularly advantageous to provide theadhesive having the passivating substance in a portion which at leastpartially delimits the region in which the technical joining connectionsare subsequently to be made. Accordingly, the first provisional fixingof the honeycomb body within the housing initially takes place in aportion other than that where the technical joining connections areultimately disposed. The method proposed herein can be carried outparticularly simply and cost-effectively even within the framework ofseries manufacture. In particular, long travels of the semifinishedproduct are avoided since, for example, transports toward furnacesand/or storage depots are avoided. Furthermore, the combination of theproposed adhesive with a passivating substance makes it possible to formpassivation layers which subsequently ensure that the technical joiningconnections are present in actual fact only in the region which has beenconfigured in terms of the thermal and dynamic loads of the catalystcarrier body.

In accordance with another mode of the invention, the passivatingsubstance is pulverulent, and it is preferably aluminum oxide, inparticular with a mean grain diameter of 0.3 to 1.5 μm. Aluminum oxidehas already proven appropriate in the past as “brazing material stop”.The mean grain diameter proposed herein proved particularly suitable inprevious tests, since a virtually closed layer was formed in this case,along with a subsequent evaporation of the adhesive. The passivationlayer produced therefore has no “free zones” in which, for example, themetal of the housing is exposed and is therefore a possible point forthe formation of technical joining connections. Alternatively or incombination therewith, it is also expedient, under certaincircum-stances, to use other refractory metal oxides such as, is forexample, zirconium oxide, magnesium oxide or the like.

It may also be mentioned, in this respect, that the volume fraction ofthe passivating substance in the adhesive is at least 40%, in particularat least 60%, and preferably at least 75%. A higher volume fraction ofthe passivating substance is to be selected, in particular, when theportion, on which the adhesive is disposed, on the inside of thehousing, has a relatively large construction, and/or when the honeycombbody is constructed with a relatively small volume. The term “smallvolume” means, in this context, that the honeycomb body has a volume(honeycomb structure including passages) which is, for example, smallerthan 1 l (liter), in particular 0.7 l, preferably smaller than 0.5 1and, particularly preferably, smaller than 0.3 l. It may also beexplained, in addition, that “mean” grain diameter means an averagevalue which characteristically describes the grain fractionconventionally used (with, for example, a Gaussian distribution of thegrain diameters).

In accordance with a further mode of the invention, placed between thehousing and the honeycomb body is at least one sleeve which ispreferably first laid around the honeycomb body and subsequently,together with the latter, introduced at least partially into thehousing. In this embodiment of the catalyst carrier body, the latterincludes at least three separate components which must be disposed in adefined position in relation to one another before they can be providedwith adhesive and brazing material which ultimately make the technicaljoining connections to the components with one another. For theformation of technical joining connections between the housing and thesleeve and/or the sleeve and the honeycomb body, band-shaped brazingmaterial strips are often used, which are fixed to the sleeve evenbefore the sleeve is inserted into the housing. In view of the problemsinitially mentioned with regard to the coordination of the technicaljoining connections with the thermal and dynamic loads on the catalystcarrier body, it is particularly important that this sleeve maintainsthe desired position in relation to the housing or in relation to thehoneycomb body until the time when the technical joining connections areactually formed. For this purpose, the adhesive having a passivatingsubstance is applied on the inside of the housing and/or the outer orinner surface area of the sleeve, so that an undesirable displacement ofthe components in relation to one another is ruled out. With regard tothe configuration of the adhesive on the sleeve, the procedure must, ingeneral, be similar to that already explained further above with regardto the inside of the housing and to the position in relation to thetechnical joining connections. With regard to the configuration of sucha sleeve, reference may be made to International Publication No. WO01/79670, corresponding to U.S. Patent Application Publication No. US2003/0007906 and International Publication No. WO 01/53668,corresponding to U.S. Patent Application Publication No. US2003/0021740, already mentioned above.

In accordance with an added mode of the invention, the adhesive isapplied on the inside of the housing in the form of a strip, inparticular so as to run completely around and preferably with a width ofless than 10 mm. Where a strip-shape of the structure is concerned, theadhesive may be disposed on the inside of the housing in one or moreportions which, for example, extend substantially or approximately inthe axial direction. Alternatively and/or additionally thereto, however,these portions may also be constructed to run around in thecircumferential direction, in particular to run around completely, so asto form virtually a ring-shaped barrier. With regard to the axial extentof the portion in which the adhesive is disposed or the passivationlayer is subsequently formed, a range of 5 mm to 50 mm is preferred. Thepassivation layer resulting therefrom has, for example, a thickness of80 μm to 120 μm.

In accordance with an additional mode of the invention, in order to formthe technical joining connections, the insertion of the honeycomb bodyinto the housing first takes place only partially, and bonding agentand/or pulverulent brazing material is then introduced by way of atleast one end face of the catalyst carrier body. With regard to thedetailed description of such a supply of bonding agent and/orpulverulent brazing material, reference is made to German Published,Non-Prosecuted Patent Application DE 101 51 487 C1, corresponding toU.S. Pat. No. 6,811,071, the contents of which are fully incorporatedherein by reference. In this case, it may also be explained that thebonding agent primarily has only the function of settling on thecomponents to be connected and of at least temporarily fixing thebrazing material subsequently supplied. A considerable bonding actionfor fixing the components themselves is not at the forefront, so that amarked difference from the properties of the adhesive can be seenherein.

In accordance with a concomitant mode of the invention, the technicaljoining connections are formed during thermal treatment. Preferably, theadhesive and the bonding agent are predominantly evaporated and, inparticular, a passivation layer is produced through the use of thepassivating substance. A high-temperature vacuum process is preferredfor the thermal treatment, with the adhesive and/or the bonding agentbeing evaporated at temperatures of below 200° C. The brazing materialin this case only begins to liquefy at higher temperatures (fromapproximately 450° C.), so that the passivation layer is formed evenbefore this liquefaction of the brazing material, and a flow of brazingmaterial beyond the passivation layer or a settling of brazing materialin the region of the passivation layer is prevented. Other featureswhich are considered as characteristic for the invention are set forthin the appended claims, the features of which can be combined with oneanother in any way desired. Although the invention is illustrated anddescribed herein as embodied in a catalyst carrier body with apassivation layer and a method for producing the same, it isnevertheless not intended to be limited to the details shown, sincevarious modifications and structural changes may be made therein withoutdeparting from the spirit of the invention and within the scope andrange of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a set of six elevational, sectional and perspective viewsdiagrammatically illustrating a sequence of production steps of a methodaccording to the invention;

FIG. 2 is an exploded perspective view showing a construction of acatalyst carrier body;

FIG. 3 is an enlarged, fragmentary, sectional view of another embodimentof a catalyst carrier body;

FIG. 4 is an exploded perspective view of a further embodiment of acatalyst carrier body;

FIG. 5 is an enlarged, fragmentary, sectional view of an embodiment of acatalyst carrier body with technical joining connections;

FIG. 6 is an elevational view illustrating a blast-cutting operation forgenerating a passivation layer; and

FIG. 7 is an enlarged sectional view of a portion VII of FIG. 6 showingthe passivation layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawings in detail and first,particularly, to FIG. 1 thereof, there is seen a diagrammaticillustration of a sequence of an embodiment of the method according tothe invention for producing a catalyst carrier body 1. Step 1 in thiscase illustrates blending and/or mixing of an adhesive 5 with apassivating substance 6. The passivating substance 6 is pulverulent andis, in particular, aluminum oxide (preferably plate-shaped particles)with a mean grain diameter 8 of 0.3 μm to 1.5 μm. The two substances aredistributed uniformly with one another, for example by using an agitatoror the like.

In step 2, a housing 2 is provided on its inside or inner surface 3 witha mixture of the adhesive 5 and of the passivating substance 6. Thehousing 2 which is illustrated in this case is shown in section. Step 3shows how a honeycomb body 4 is inserted at least partially into thehousing 2. The honeycomb body 4 is preferably a metallic honeycomb body4 and the housing 2 is also preferably made from metal.

Step 4 shows one possibility of how a bonding agent 12 can be introducedinto inner regions of the honeycomb body 4 or of the housing 2. Thebonding agent 12 in this case is introduced into the honeycomb body 4,for example using a capillary plunger or a distributor 24, in such a waythat the distributor 24 comes into contact with an end face 11 of thehoneycomb body 4. The distributor 24 has a multiplicity of passages inwhich the bonding agent 12 has located itself. Upon contact with thehoneycomb body 4, the bonding agent 12 rises into passages 15 (see Step3) as a result of a capillary effect, thus wetting regions to besubsequently provided with brazing material.

Step 5 shows a fluidized bed 25, through the use of which pulverulentbrazing material 13 is injected into inner regions of the catalystcarrier body 1. The brazing material 13 in this case remains adhering tothe non-illustrated bonding agent 12.

Step 6 diagrammatically shows a catalyst carrier body 1 in a furnace 26.In this case, a thermal treatment of the catalyst carrier body iscarried out, in which, initially, the introduced adhesive 5 isevaporated and a passivation layer is formed, before the brazingmaterial 13 liquefies. After the thermal treatment or during the coolingof the catalyst carrier body, the previously liquid brazing materialsolidifies, and the individual components of the catalyst carrier bodyare connected to one another. This last method step preferably involveshigh-temperature vacuum brazing.

FIG. 2 diagrammatically shows an embodiment of a catalyst carrier body 1with a sleeve 9, in an exploded illustration. A first component of thecatalyst carrier body is the honeycomb body 4. The latter includes amultiplicity of metallic sheet metal layers 16 which are constructed tobe partly smooth and partly structured and have been layered alternatelyand subsequently wound or intertwined with one another. The sheet metallayers 16 in this case have a thickness which is preferably less than 50μm, in particular less than 20 μm, and preferably less than 15 μm. Withregard to the production or configuration of the sheet metal layers forsuch a honeycomb body 4, reference may be made at this juncture toEuropean Patent Application 0 245 737 A1, corresponding to U.S. Pat.Nos. 4,803,189, 4,832,998, 4,923,109 and 4,946,822; InternationalPublication No. WO 90/03220, corresponding to U.S. Pat. Nos. 5,105,539and 5,135,794; and German Patent DE 37 43 723 C1, the contents of whichare fully incorporated herein by reference. In the illustratedembodiment, the sheet metal layers 16 are wound in an approximatelyS-shaped manner, and ends 21 of the sheet metal layers 16 can be seen atthe periphery. Due to the structuring of some sheet metal sheets 16,passages 15 are formed, which extend substantially or approximatelyparallel to an axis 17 of the catalyst carrier body 1 and are delimitedby the end faces 11 of the honeycomb body 4. In other words, thepassages 15 correspond substantially or approximately to a length 18 ofthe honeycomb body 4.

The catalyst carrier body 1 is delimited outwardly by the housing 2which has an extent 23 in the direction of the axis 17. The sleeve 9which is disposed between the honeycomb body 4 and the housing 2 has anextent 22 in the direction of an axis 17. In order to produce such acatalyst carrier body 1, first, the honeycomb body 4 and the sleeve 9are produced separately, the honeycomb body 4 subsequently beingintroduced into the sleeve. The non-illustrated adhesive 5 having thepassivating substance 6, which is provided on the inside 3 of thehousing 2, initially ensures fixing within the housing 2 immediatelyafter the sleeve 9 is pushed in together with the honeycomb body 4.Brazing of the catalyst carrier body 1 on the end face and concludingthermal treatment are subsequently carried out, in which technicaljoining connections are produced that are not positioned in the regionof the non-illustrated previously applied adhesive 5. In principle, theconfiguration of the catalyst carrier body 1 in terms of the length 18of the honeycomb body 4, of the extent 22 of the sleeve 9 and/or of theextent 23 of the housing 2 is freely selectable, so that not allcomponents have to be flush with one another at the end faces 11.

FIG. 3 shows a view of a portion of a catalyst carrier body 1 insection. This figure partially illustrates a housing 2 and a honeycombbody 4 (identified by components 15 and 16) formed from sheet metallayers 16 and having passages 15, with a sleeve 9 being disposed betweenthe housing 2 and the honeycomb body 4. The illustrated section lies ina region of the catalyst carrier body 1 in which no connections aredesired between the sleeve 9 and the housing 2 or the honeycomb body 4.In this region, therefore, in each case adhesive 5 having a passivatingsubstance 6 is provided between the sleeve 9 and the housing 2 andbetween the sleeve 9 and the sheet metal layers 16. The embodiment shownherein constitutes virtually a semi-finished product. After the thermaltreatment of the catalyst carrier body 1, a continuous passivation layer14 (see FIG. 4) is formed from the passivating substance 6 between thesleeve 9 and the adjacent components 2, 4.

FIG. 4 is a perspective view of a further embodiment of a catalystcarrier body 1 including a honeycomb body 4 and a housing 2. Thehoneycomb body 4 is again constructed with a plurality of sheet metallayers 16. A tying or connection region 20 of the honeycomb body 4 tothe housing 2 in this case is illustrated by hatching. The tying region20 is the region in which a technical joining connection of thehoneycomb body 4 or of the sheet metal layers 16 to the housing 2 issubsequently effected. Moreover, the adhesive 5 including thepassivating substance 6 was provided on the inside 3 of the housing 2 sothat, during the subsequent thermal treatment, passivation layers 14running completely around in strip form and having a width 10 (also seeFIG. 1, Step 2) which is smaller than 10 mm are generated. As isevident, the passivation layers 14 are disposed in such a way that theydelimit the tying region 20 after the honeycomb body 4 has been pushedcompletely into the housing 2. This prevents auxiliary or processmaterials for the formation of technical joining connections fromflowing beyond the limits of the tying region 20 and from causingundesirable connections there. While one passivation layer 14 isdisposed directly at one end face 11 of the honeycomb body 4, the otherpassivation layer 14 is disposed at a distance 19 from an end face 11,in the direction of the axis 17.

FIG. 5 shows a further view of a portion of an embodiment of a catalystcarrier body with a housing 2, with a sleeve 9 and with sheet metallayers 16 forming a honeycomb body 4. This figure is intendedparticularly to illustrate the formation of technical joiningconnections 7 which are preferably formed in the contact regions of thecomponents 2, 9, 16 disposed adjacently one another. In this case, theformation of such connections 7 takes place solely in the tying region20, since there is no passivation layer 14 provided therein.

FIG. 6 is a diagrammatic illustration of a blast-cutting operation forgenerating the passivation layer. Corundum particles 29 with a size 28of 10 μm to 20 μm are blasted onto a sleeve 9 (or onto the inside 3 ofthe housing 2) through the use of a nozzle 32. For this purpose, anenergy carrier 31 such as, for example, air or a liquid, to which thecorundum particles 29 are supplied, is used. The latter are entrainedand impinge onto the surface of the sleeve 9 or the inside 3. In thiscase, on one hand, the surface of the sleeve 9 or the inside 3 isscored, stripped off, etc. but, on the other hand, splitting of thecorundum particles and settlement of subfragments on the roughenedsurface also take place.

This surface of the sleeve 9 or the inside 3 with the passivation layer14 is illustrated diagrammatically in FIG. 7. The passivation layer 14includes a multiplicity of separate or isolated crystal agglomerations27 having an averaged height 30 which is in the range of 0.3 to 1.5 μm.The term “height 30” means the amount by which the crystalagglomerations 27 project with respect to a surrounding level 33 of thepassivation layer 14.

The method described herein is particularly simple and cost-effective,so that it is predestined for use in series manufacture. The catalystcarrier bodies resulting from this method are capable, over a longperiod of time, of withstanding the thermal and dynamic loads in theexhaust system of a motor vehicle.

1. A catalyst carrier body, comprising: at least one housing having aninside; a honeycomb body connected to said inside of said at least onehousing by technical joining in a tying region; and at least onepassivation layer delimiting said tying region, said passivation layerincluding a multiplicity of separate crystal agglomerations with anaveraged height lying in a range of 0.3 to 1.5 μm.
 2. The catalystcarrier body according to claim 1, wherein said crystal agglomerationsare disposed on said inside of said housing.
 3. The catalyst carrierbody according to claim 2, wherein said inside of said housing isroughened in the vicinity of said passivation layer.
 4. The catalystcarrier body according to claim 1, further comprising at least onesleeve disposed between said housing and said honeycomb body, saidcrystal agglomerations being disposed on said at least one sleeve. 5.The catalyst carrier body according to claim 4, wherein said sleeve isroughened in the vicinity of said passivation layer.
 6. A method forproducing a catalyst carrier body, which comprises the following steps:providing at least one housing having an inside; providing a honeycombbody; roughening a region of at least one of the inside of the housingor the honeycomb body using a blast-cutting manufacturing method withcorundum particles employed as a blasting medium; inserting thehoneycomb body into the housing; and forming technical joiningconnections between the honeycomb body and the housing.
 7. A method forproducing a catalyst carrier body, which comprises the following steps:providing at least one housing with an inside; providing at least onesleeve; providing a honeycomb body; roughening a region of the sleeveusing a blast-cutting manufacturing method with corundum particlesemployed as a blasting medium; assembling the housing as an outercomponent, the honeycomb body as an inner component and the at least onesleeve between the housing and the honeycomb body; and forming technicaljoining connections between the honeycomb body, the at least one sleeveand the housing.
 8. A method for producing a catalyst carrier body,which comprises the following steps: providing at least one housing withan inside; providing a honeycomb body; at least one of blending ormixing an adhesive with a passivating substance; applying the adhesivehaving the passivating substance to the inside of the housing; insertingthe honeycomb body into the housing; and forming technical joiningconnections between the honeycomb body and the housing.
 9. The methodaccording to claim 8, wherein the passivating substance is pulverulent.10. The method according to claim 8, wherein the passivating substanceis aluminum oxide.
 11. The method according to claim 9, wherein thepassivating substance has a mean grain diameter of 0.3 to 1.5 μm. 12.The method according to claim 10, wherein the passivating substance hasa mean grain diameter of 0.3 to 1.5 μm.
 13. The method according toclaim 8, which further comprises placing at least one sleeve between thehousing and the honeycomb body.
 14. The method according to claim 13,which further comprises carrying out the placing step by initiallyplacing the at least one sleeve around the honeycomb body andsubsequently at least partially introducing the at least one sleevetogether with the honeycomb body into the housing.
 15. The methodaccording to claim 8, which further comprises carrying out the step ofapplying the adhesive by applying the adhesive to the inside of thehousing in the form of a strip.
 16. The method according to claim 15,which further comprises extending the strip completely around thehousing.
 17. The method according to claim 15, wherein the strip has awidth smaller than 10 mm.
 18. The method according to claim 8, whichfurther comprises carrying out the step of inserting the honeycomb bodyinto the housing by initially only partially inserting the honeycombbody into the housing and then introducing at least one of a bondingagent or a pulverulent brazing material from at least one end face ofthe catalyst carrier body.
 19. The method according to claim 8, whichfurther comprises carrying out the step of forming the technical joiningconnections during thermal treatment.
 20. The method according to claim19, which further comprises predominantly evaporating the adhesive andthe bonding agent during the thermal treatment.
 21. The method accordingto claim 20, which further comprises producing a passivation layerthrough the use of the passivating substance.
 22. The method accordingto claim 6, which further comprises connecting the honeycomb body to theinside of the at least one housing by technical joining in a tyingregion, and delimiting the tying region with at least one passivationlayer including a multiplicity of separate crystal agglomerations withan averaged height lying in a range of 0.3 to 1.5 μm.
 23. The methodaccording to claim 7, which further comprises interconnecting thehoneycomb body, the at least one sleeve and the at least one housing bytechnical joining in a tying region, and delimiting the tying regionwith at least one passivation layer including a multiplicity of separatecrystal agglomerations with an averaged height lying in a range of 0.3to 1.5 μm.
 24. The method according to claim 8, which further comprisesconnecting the honeycomb body to the inside of the at least one housingby technical joining in a tying region, and delimiting the tying regionwith at least one passivation layer including a multiplicity of separatecrystal agglomerations with an averaged height lying in a range of 0.3to 1.5 μm.